If you’re confused, know that you’re not alone. Both infant and convertible car seats can be used by infants. But aside from that, there are some major differences to consider before you make a purchase.

• Infant car seats: These seats are rear-facing only, have a lower weight limit than convertible car seats and can usually be used until your baby is 22 to 35 pounds and 26 to 35 inches (this will vary a bit by model). You won’t be able to use infant car seats as long as convertible car seats, but they do have some clear benefits, the main one being portability. Infant car seats are smaller than convertible car seats, have carrying handles and can be easily clicked in and out of their base.
• Convertible car seats: Unlike infant car seats, convertible models can be both rear- and forward-facing. You can use them when your baby is a newborn until she reaches the maximum weight or height requirement for the seat’s forward-facing position, which is usually sometime in the preschool years (though some models can extend much longer). This can be a smart investment: “If cost is a large concern, you may want to consider a car seat that is not only fit for an infant but converts to a forward facing car seat which can save a considerable amount,” says Dr. Chan. The downside is that you won’t be able to use a convertible car seat as part of a travel system, and it’s not nearly as portable.

This comes down to personal preference and lifestyle. But generally:

An infant car seat might be right for you if:

• You want to be able to use your child’s car seat as part of a travel system
• Your child will be a passenger in a few different cars (yours, your partner’s, a grandparent’s) and you don’t want to buy a separate car seat for each

A convertible car seat might be right for you if:

• You want to invest in one car seat when your baby is a newborn and not replace it for many years
• You don’t mind not being able to easily take your child’s car seat in and out of the car or use it as a stroller attachment

This will depend on the specific make and model of car seat you purchase as well as how quickly your baby reaches the maximum weight or height requirements. Infant car seats have height and weight limits, and should no longer be used once your child reaches either milestone. In other words, if baby has met the height limit but is under the weight limit, you'll still have to retire your infant car seat. 

Exact height and weight limits vary from model to model — check your car seat’s manual for your seat’s limits — but most infant car seats have a height limit somewhere between 30 and 35 inches (or when your child’s head is less than one inch from the top of the carrier), and a weight limit between 30 and 35 pounds.

Some babies will outgrow their infant car seats before their first birthday, while others can continue using these seats for longer. If longevity is a priority, look for an infant car seat with higher height and weight maximums.